Presence service refers to a service that makes the state of a service presence client visible to a selected presence contact, so as to make it possible for the contact to choose appropriate communication means, time and communication service of his/her own. Presence information refers to the current state of a presence client, including online/offline, busy/idle, etc. The state, e.g., online or offline, can be obtained through detecting a network connection between a presence server and a presence client end. The state can also be configured by a client who uses the presence client end, e.g., be configured to be in a meeting, etc. The state still can be obtained through detection by a presence client end software. For example, if the client end software has not detected any information inputted by the client for a period of time, it sets the presence information of the client as leaving. A Presence contact refers to a presence client who has subscribed presence information of another presence client. For the presence client whose presence information has been subscribed by other presence client, the other presence client is called a “contact”. The presence service has been integrated into various Instant Messaging (IM) software programs.
As shown in FIG. 1, a conceptive model of a presence system includes three components: a presence server, a presence client end and a presence contact end. The presence server includes a hardware device and software for providing a presence service. The presence client end includes a terminal equipment and software used to log in the presence system for a presence client. The presence contact end includes a terminal and a software program, used to log in the presence system for a presence contact. It should be noted that, to make the description convenient, the presence client end and the presence contact end are described separately. Whereas in practical presence services, the presence client and the presence contact tend to be contacts to each other, and they run the same software program.
Before obtaining the presence information of a presence client, a presence contact must subscribe for the presence information of the presence client from the presence server. The presence server adds the presence client to a presence information subscription list of the presence contact after authentication. When the state of the presence client changes, the presence server can obtain the state information of the presence client through various methods, including:
1) monitoring a communication interface between the presence server and the presence client end by the presence server, e.g., monitoring whether the presence client has logged on the client end software, etc.;
2) configured by the presence client his/her own, e.g., configured to be in a meeting, and reported to the presence server by the presence client;
3) monitored by the presence client, e.g., if the client software has not detected any input from the presence client for a period of time, the client end software configures the presence information of the presence client as leaving, and reports the state information to the presence server through the presence client end.
Upon detecting the change of the presence state of the presence client, the presence server distributes presence information to the presence contact who has subscribed for the presence information of the presence client. Upon receiving the presence information, the presence contact end correspondingly changes the presence information of the presence client displayed on a terminal interface, e.g., changes the presence information from “online” to “busy”.
Through the above mentioned techniques, in the current presence system, a client can make it convenient for his/her contact to see various state information configured by the client or detected by a computer. So that the contact can arrange communication manner and communication time according to the state information.
Whereas, traditional telephone still plays a very important part in people's everyday life and work, and it is a main communication means for people. A telephone client also expects to let his/her telephone state information known by his/her contact, therefore the contact can choose a corresponding communication mode and time according to the telephone state of the client when calling the client. Thus, the contact may not call the client when the client is busy according to the telephone state of the client.
If the presence system does not have the ability of providing telephone state information, a presence contact cannot know the telephone state of a presence client. Thus, when needs to call the client, the contact often encounters a busy telephone line. If the contact does not know when the client's telephone will be idle, he can only dial for many times, which wastes a lot of time and energy.
To solve this problem, a solution on basis of a telephone switch is proposed to implement the presence service of the telephone state information. As shown in FIG. 2, the solution is implemented through modifying the program of the telephone switch. Upon detecting a change on the telephone state, the telephone switch sends a notification of telephone state change information to the presence server. And the corresponding presence server has been configured with data related to the telephone state information. Upon receiving the notification of the telephone state change information, the presence server looks for the presence client information corresponding to the telephone number, modifies the presence information related to the telephone state, and distributes the telephone state change information to the contact who has subscribed for the presence information of the client.
Whereas, the solution has the following problems:
1) the cost is high.
In this solution, the program of the telephone switch needs to be modified, that is to say, to implement a presence service of the telephone state information, a large scale telephone switch reconstructions must be performed by telecommunication operators or vendors.
2) the solution depends on the ability of a telephone switch
The reconstruction of the switch cannot be implemented in a short time, so that a client can only enjoy the service in an area where the reconstruction is finished, once leaving the area, the client cannot use the service any more, i.e., the client cannot present the telephone state to his/her contact.